This invention relates to a chair for keeping the lumbar spine of a person seated in the chair in a position of lumbar lordosis. Lumbar lordosis is the natural position of the spine and is a protecting mechanism for the low back or lumbar spine. It is the position best suited for protecting the lumbar disc and the lumbar spine
It is estimated that neck and back pain afflict as many as 90% of the population of the United States at some time during their lives. Back and neck pain are conditions very frequently seen on a regular basis by many physicians and other medical practitioners. Due to the sedentary nature of many individuals, sitting in a poor position is one of the causative or aggravating factors for individuals with low back and neck pain. Moreover, poor posture and poor sitting have been identified by many spine experts as an aggravating factor for individuals with cervical and lumbar spine problems.
The lumbar lordosis is the inward curve in the lumbar spine (concavity) that is the normal curve of the spine. As illustrated in FIG. 1, the lordosis is related to the position of the pelvis. When the pelvis is positioned in a position of anterior rotation or tilt, the lordosis is accentuated or maintained. However, as illustrated in FIG. 2, when a person sits in a slouched position, the pelvis is positioned in a position of posterior pelvic tilt and the lordosis is diminished or lost. The anterior pelvic tilt that is desired can be achieved by allowing the knees to be placed in a position that is lower than the hip joints. By positioning the knees lower than the hips, a stretch is placed on the anterior structures of the hip joint including the flexors of the hip. This stretch assists the pelvis in tilting anteriorly which is desirable. On the other hand, if the knee joint is placed above or level with the hip joint, then a stretch is taken off the anterior structures and the pelvis will rotate posteriorly and the lumbar lordosis will be lost.
There have been many recent attempts to design chairs to prevent low back and neck pain. However, none of these attempts have been completely successful because they attempt to maintain the lordosis using only a lumbar roll in the back of the chair.